When Shortage Notification has been enabled for a component part, it will be shortage listed when an unsuccessful attempt to reserve it to a shop order is made. The shortage will then be listed on Shop Order Materials with Shortage page.

When a shortage listed part is received to stock, a message will appear that shortages exists.

Then the received quantity will be visible as Qty to Distribute field on Shop Order Materials with Shortage page. Maybe an event/action could triggered when a value higher than 0 appears in this table since that indicates a shortage listed component now has a quantity available to be reserved in stock?